The role of aluminum doping in shaping the mechanical properties of p-type 4H-SiC†

In p-type 4H-SiC crystals, the doping of aluminum (Al) will affect mechanical properties due to changes in the crystal structure and defect dynamics. This study employs nanoindentation, Raman spectroscopy, and transmission electron microscopy (TEM) to investigate the effects of Al doping on the mechanical properties of p-type 4H-SiC. It compares samples with varying Al concentrations (undoped, low Al-doped, and high Al-doped) to examine changes in elastic modulus, hardness, and fracture toughness. Nanoindentation results reveal that Al doping reduces the hardness and fracture toughness of 4H-SiC, with the impact becoming more pronounced as the doping level increases. Microstructural analysis shows that Al doping facilitates dislocation formation and crack propagation, contributing to the observed mechanical degradation. Additionally, first-principles calculations provide insight into the underlying mechanisms, confirming that Al doping reduces the elastic modulus, hardness, and fracture toughness due to changes in shear modulus and bond strength. This work enhances the understanding of doping effects in p-type 4H-SiC and provides valuable information for the design and optimization of high-performance SiC wafers for industrial applications.